Pneumatic blow-out in circuit breakers



April 21, 1959 A. LATOUR 2,883,494

PNEUMATIC BLOW-OUT IN CIRCUIT BREAKERS Filed Dec. 1. 1955 2 Sheets-Sheet 1 Fig. 1 F g- 16 17 Fig. 4

g 2 Fig. 5

H 22 1s V v 19 INVENTOR.

Andr LATOU R A A 41mm Attorney A ril 21, 1959 A. LATOUR PNEUMATIC BLOW-OUT IN CIRCUIT BREAKERS Filed Dec. 1. 1953 Fig 11 2 Sheets-Sheet 2 INVENTOR. Andr LATOU R BY k wk W United States Patent PNEUMATIC BLOW-OUT IN CIRCUIT BREAKERS Andr Latour, Grenoble, France, assignor to Etablissements Merlin & Gerin, Grenoble, France Application December 1, 1953, Serial No. 395,565 Claims priority, application Belgium January 13, 1953 Claims. (Cl. 200-148) The invention relates to electric interrupters or circuit breakers which effect the extinction of the are through or after division or elongation of the are or both, be it in the interior of a current breaking chamber, or be it even in the free atmosphere.

These interrupters generally are operative through the so-called magnetic blow-out, or, in certain cases, also through combination or addition of electromagnetic and eiectrodynamic effects.

For weak currents however, for instance when arcs of high tension and low intensity are to be extinguished, the electromagnetic or electrodynamic effects will be insufiicient. It has therefore been suggested to employ a jet of air transversely of the path of the arc in order to obtain a large loop of the arc, to displace the roots of the are rapidly upon the are drawing and extinguishing contacts, and, eventually, cause the penetration of the are into the current breaking and extinguishing chamber or, the case given, between the partitions which subdivide the are breaking or extingushing chamber.

However, such an air jet drives the median part of the arc outwards, but the lateral parts of the arc cling to the jet at both its sides and the roots of the arc stay at or near the places upon the arc drawing-contact wherefrom the arc starts its initial development and expansion so that the results of such an arrangement are unsatisfactory.

It is thus particularly an object of the invention to avoid the disadvantages of such an arrangement.

The inventor has recognized that the cause of this unsatisfactory operation of an air jet lies in the phenomenon that the air, which moves with high velocity, produces a suction effect on the ambient medium which as a result draws the gaseous molecules of the vicinity towards the concentrated blast column. The body of the are thus is deformed with two lateral branches which tend to cling along the jet whilst, likewise owing to the suction efiect, the roots of the are upon the arc drawing contacts are solicited in a direction rather opposite to that which is desired. Should even the air jet be made movable in order to sweep successively the various parts of the are drawing and extinguishing chamber, the result would not be better, the arc would be displaced together with the jet without however expanding as desired.

The inventor has now made the discovery that these effects of the suction may be avoided and a satisfactory development of the are be obtained in accordance with the invention when in the device for the pneumatic blowout of an electric are by displacing it along and expanding it between the are drawing and extinguishing contacts of a circuit breaker, the air blast nozzle has an orifice with a passage spreading outwardly fan-wise in the plane of the arc development and expansion, the jet ejected from the air blast nozzle thus being in the shape of a fan the plane of which is that within which the are 2,883,494 Patented Apr. 21, 1959 is to be displaced. Preferably, the fan-wise spread opening is conically enlarged towards the sides and is of a width such that the air blast sweeps directly the arc drawing contacts together with the space therebetween. A large part, if not the whole of the chamber thus is subjected simultaneously to the action of the air current.

In order to obtain a jet of fan-shape a tube may be employed the orifice of which has been conveniently flattened. This orifice may present itself in the form of a greatly elongated ellipse, or of a rectangular slot, or may be of saw teeth form. Several small blow orifices may be arranged so that the orifice comprises a set of ducts or bores through the otherwise closed head of the nozzle and spread in fan-wise arrangement with diverging axes, corresponding to the rays of the fan which are to be obtained. The nozzle may also comprise two jets directed towards each other similar to the two jets of a burner of the butterfly type. The jet or the jets may also be directed upon a plane surface, for instance upon the lateral face of one of the contacts, upon which it breaks and displays or expands in fan-shape. It will be understood that generally any convenient or conventional means may be utilized through which a fan-shaped jet is ejected from a nozzle.

The invention will now be described more specifically with reference to the accompanying drawings which form part of this specification and which by way of example illustrate various embodiments of the invention. These drawings are to be understood explicative of the invention but not limitative of its scope. Other embodiments incorporating the principle underlying my invention are feasible without departing from the spirit and ambit of my appended claims.

In the drawings:

Fig. 1 is a fractional elevational view partly in section of an are drawing chamber with a conventional blow nozzle of cylindric form;

Fig. 2 is a similar view of an are drawing chamber provided with a nozzle of an orifice with a fan-wise spread passage in accordance with the invention;

Figs. 3 and 4; 5 and 6; 7 and 8; 9 and 10, respectively are elevational sections and top views of the head parts of nozzles of the invention for fan-wise spreading the blow jet;

Fig. 11 is a fractional elevational view, partly in section, of an are drawing chamber with a blow nozzle of the invention with asymmetric head and asymmetrically disposed relatively to the are drawing contacts; and

Fig. 12 is a similar view of an arc drawing chamber provided with a blow nozzle of the invention movable with the mobile contact of a circuit breaker.

In the drawings, 11 and 12 are the are drawing contacts or arc horns, along which the roots of the are are to be displaced, the purpose of these contacts being to allow the current breaking are to expand and to rise into the interior of the current breaking chamber. These contacts are disposed preponderantly in a symmetry plane of the circuit breaker, viz. the plane in which the arc is to develop and expand. The operative or are extinguishing part of this chamber may be formed by a series or stack of plates 13, schematically and diagrammatically indicated in Figs. 1, 2, 11, and 12, perpendicularly to the plane of the figures. Through these plates, the are, when it penetrates between them, is subdivided or elongated or both, ever according to the type of plates, insulating, or conductive, or both. Since the invention refers to the phase which separates the formation of thearc from the penetration of the are into the are extin-.

guishing chamber and does not refer to the extinction of the arc between these plates, the chamber will herein neither be illustrated nor described in detail nor will the mode of its function, a function which may take place in various ways known per se and which now are utilized currently in the art.

In the absence of noticeable electrodynamic or electromagnetic forceswhich practically do not exist withweak currents, air blasts have been employed which force the arc to penetrate into the system formed by the set of plates 13, or, which, if the plates carry at their lower parts metallic conductors, force the arc to attach itself to these conductors.

Fig. 1, thus, by way of comparison, illustrates a conventional air blast nozzle 14 which directs an air jet 15, approximately cylindrical or even slightly conical, transversely of the are. In order to simplify the disclosure, in this arrangement, and also in those of Figs. 2 and 11, the arc is supposed to have already been drawn between two contacts, in a manner not shown on the drawings, and to have attached itself at 16 and 17, Fig. l, to the arc drawing contacts 11 and 12. For the reasons set forth hereinabove, the effect of such a jet is unsatisfactory. Outside the region which the jet immediately sweeps, the ambient medium is energetically drawn to the jet with the result that the parts of the electric are at the sides of the jet cannot freely develop but, as Fig. 1 illustrates, cling to the jet and follow it with two more or less parallel branches. No driving force remains which would compel the roots of the arc to advance from the points 16, 17, and to rise along the arc drawing contacts 11, 12, the suction created by the jet rather causes the roots to descend. The eliect of the jet thus is limited to the narrow region which the jet sweeps. Only a small portion of the arc is directly driven by the jet into the chamber 13. The rest escapes the blowing action and, since the two branches of the arc which cling to the jet are separated from each other only through the relatively small diameter or thickness of the jet, a short-circuit of the initially formed are may be caused.

Contrariwise, if in accordance with the present invention, a jet of fan-shape is utilized in the plane in which the arc develops, or in the plane of the drawing, Fig. 2, the are on a substantial part of its length if not on its entire length is subjected to the action of the air blast. Moreover, the roots of the arc are directly driven to the ends 18, 19 of the inclined parts of the contacts. The extinguishing effect of the chamber 13, whichever the mode of its operation may be, will thus become effective over a length of the are which is a multiple of that of Fig. 1. The efficiency of the chamber thus is increased and, finally, the risk of a short-circuit is obviously excluded.

' The nozzles may be of various types.

In the embodiment of Figs. 2 to 4, the fan-shape of the jet is obtained by means of a nozzle 20 which is flattened from a cylindrical tube 21 so that towards the sides a conically enlarged, otherwise narrowed orifice with correspondingly elongated mouth results.

In the arrangement of Figs. and 6, the orifice of the nozzle 22 is produced through an oblique slot 23 through the otherwise closed head or cap 24 of the nozzle.

Figs. 7 and 8 illustrate a nozzle 25 with a head 26 comprising two orifices 27, 28 directed generally towards each other, similar to the two jets of a butterfly burner.

. In the arrangement of Figs. 9 and 10, the jet in fanshape results from a series of elementary jets obtained by means of a range of openings or ducts 31, 32, 33, 34, worked into a head piece or cap 35 which otherwise closes the blow conduit 36.

The orifice need not be symmetric with regard to the axis of the nozzle but may be asymmetric as Figs. 9 and illustrate. Ever according to the position of such an asymmetric nozzle with relation to the fixed and mobile contacts, for instance of the nozzle 39 with flattened,

asymmetric, conically spread orifice 40, Fig. 11, the jet 4 may be oriented in the sense whichever appears to be the most favorable, always under the condition that the fan-wise spreading of the jet ensues in the plane in which the arc is to be developed and expanded, as Fig. 11 illustrates.

Furthermore, the jet need not sweep simultaneously the whole of the chamber 13 as hereinabove described with reference to Figs. 2 and 11. Particularly, as Fig. 12 illustrates, the nozzle 41, 42, appropriately secured to the mobile contact 43, by means not shown here in detail, may be displaced together with the mobile contact and thus on the course of its displacement may sweep successively the various regions of the chamber. Fig. 12 illustrates two positions, the one in full lines corresponding to the closed position of the mobile contact, the other in broken lines to the open position of this contact. The blowing eifect will set in with the moment at which the contacts open and the arc is drawn and will effectively follow the development and expansion of the arc.

I claim:

1. An electric circuit breaker of the magnetic blow-out type comprising an arc chute and pneumatic means for driving the are into the arc chute, such pneumatic means including a nozzle for an air jet, and means defining an orifice in the nozzle having a passage spreading outwardly fan-wise in the plane of the arc development and expansion, the orifice comprising a set of ducts through the otherwise closed head of the nozzle and with diverging axes in fan-wise spread arrangement.

2. An electric circuit breaker of the magnetic blow-out type comprising an arc chute and pneumatic means for driving the are into the arc chute, such pneumatic means including a nozzle for an air jet, and means defining an orifice in the nozzle having a passage spreading outwardly fan-wise in the plane of the arc development and expension, the nozzle comprising two orifices generally directed towards each other similar to the two jets of a butterfly burner.

3. An electric circuit breaker of the magnetic blow-out type comprising an arc chute and pneumatic means for driving the are into the arc chute, such pneumatic means including a nozzle for an air jet, and means defining an orifice in the nozzle having a passage spreading outwardly fan-wise in the plane of the are development and expansion, the orifice comprising an oblique slot through the otherwise closed head of the nozzle.

4. An electric circuit breaker of the magnetic blow-out type having an arc developing chamber, an arc extinguishing chamber, at least one mobile contact and a pair of are drawing contacts diverging within the arc developing chamber towards the arc extinguishing chamber; said circuit breaker including an air blast nozzle having an orifice with a flat passage diverging in the plane of the arc development and expansion; said air blast nozzle being disposed at said mobile contact so as to be displaceable therewith, said nozzle being further shaped and disposed so as for the air jet, following the movement of the mobile contact and the development and expansion of the arc, to sweep, while being displaced, over and across the space between and above the contacts and the roots along the contacts and thus to sweep successively the entire arc development and expansion space.

5. An electric circuit breaker of the magnetic blowout type having an are developing chamber, an are extinguishing chamber, and a pair of arc drawing contacts diverging within the are developing chamber towards the arc extinguishing chamber; said circuit breaker including an air blast nozzle displaceable across the plane of the arc development and expansion, said nozzle having an orifice with a passage spreading outwardly fan-wise in said plane of the arc development and expansion, said nozzle being further shaped and disposed relatively to said contacts and the space confined therebetween, so as, for the air jet ejected from the nozzle on movement thereof, to sweep successively said space, from contact to 5 contact, and displace the roots of the are along said di- 2,347,984 verging contacts and the arc through the are developing 2,349,681 chamber into the arc extinguishing chamber. 2,491,964

References Cited in the file of this patent 5 UNITED STATES PATENTS 299 700 1,334,645 Beehofi et a1. Mar. 23, 1920 600,686

6 Baskerville May 2, 1944 Slepian May 23, 1944 Frink Dec. 20, 1949 FOREIGN PATENTS Great Britain Aug. 1, 1929 Germany July 28, 1934 

